This is the fifth article in a series on common usability and graphical user interface related terms [part I | part II | part III | part IV]. On the internet, and especially in forum discussions like we all have here on OSNews, it is almost certain that in any given discussion, someone will most likely bring up usability and GUI related terms - things like spatial memory, widgets, consistency, Fitts' Law, and more. The aim of this series is to explain these terms, learn something about their origins, and finally rate their importance in the field of usability and (graphical) user interface design. In part V, we focus on modes.

"What about CAPS LOCK key - there's only one key worse than it - I mean NUM LOCK key. I've recieved many calls about "I can't enter any numbers into Excel datasheet", hitting NumLock has resolved all these problems "

Risking to get more off topic with this, you'll find a similar some entries here:

Furthermore, the Num Lock key is a basal means of diagnostics - if switching the Num LED off and on still works, a defect can't be that bad. :-)

Num Lock is an artifact from the XT and early AT era when there were no separated cursor keys. Num Lock made you use the numeric keypad for entering numbers and for cursor control. Today, this choice is obsoleted with the MF-2 style keyboards where both functionality groups are present at one time, so this key is hardly used.